Changes in the metabolism of methionine can cause hyperhomocysteinemia, inducing a triad of atherosclerosis, hypertension, and increased oxidative stress. The generation of free radicals and oxidative damage to DNA is important in the liver damage caused by ethanol. In this study, the effect of methionine overload associated or otherwise with acute administration of ethanol on homocysteine values, damage to DNA, lipoperoxidation and vitamin E was evaluated. Thirty rats were divided into 3 groups: Group Ethanol 24 hours (EG24), Group Methionine 24 hours (MG24), and Group Methionine and Ethanol 24 hours (MEG24). TBARS, vitamin E, GS and, homocysteine values were determined and the Comet assay was carried out. Increased GSH, vitamin E and homocysteine levels were observed for MEG24, and increased TBARS were observed in EG24. The Comet assay showed an increase in DNA damage in EG24 and DNA protection in MEG24. The administration of ethanol decreased antioxidant levels and increased TBARS, indicating the occurrence of oxidative stress with possible DNA damage. The combination of methionine and ethanol had a protective effect against the ethanol-induced damage, but increased the levels of homocysteine.; Alterações no metabolismo da metionina podem ocasionar hiper-homocisteinemia...

Biological activities of flavonoids have been extensively reviewed in literature. The biochemical profile of afzelin, kaempferitrin, and pterogynoside acting on reactive oxygen species was investigated in this paper. The flavonoids were able to act as scavengers of the superoxide anion, hypochlorous acid and taurine chloramine. Although flavonoids are naturally occurring substances in plants which antioxidant activities have been widely advertised as beneficial, afzelin, kaempferitrin, and pterogynoside were able to promote cytotoxic effect. In red blood cells this toxicity was enhanced, depending on flavonoids concentration, in the presence of hypochlorous acid, but reduced in the presence of 2,20 -azo-bis(2-amidinopropane) free radical. These flavonoids had also promoted the death of neutrophils, which was exacerbated when the oxidative burst was initiated by phorbol miristate acetate. Therefore, despite their well-known scavenging action toward free radicals and oxidants, these compounds could be very harmful to living organisms through their action over erythrocytes and neutrophils.

Reactive oxygen species (ROS) and free radical species have been implicated in initiating or accompanying many diseases in living organisms; there is thus, a continual need for antioxidants molecules to inactivate ROS/free radicals. Many studies of plants crude extracts have demonstrated free-radical scavenging and antioxidant action. Salacia species have long been used, in several countries, as traditional medicines against certain diseases and for their anti-inflammatory properties. In this study, Salacia campestris Walp (Hippocrateaceae) root bark ethanol extract (ScEtOH) was assessed for its ability to scavenge free radicals and reactive oxygen species; the results were expressed as percentage inhibition of the active species. ScEtOH was efficient against studied species: DPPH radical (obtained inhibition = 30%), ABTS+ (IC50 = 1.8±0.8 μg/mL), HOCl (IC50 = 1.7 ± 0.1 μg/mL), O2- (obtained inhibition = 32%), and NO (obtained inhibition = 18 %). Peroxidase activity inhibition was evaluated through the guaiacol oxidation reaction catalyzed by hemin, HRP and myeloperoxidase (MPO); data showed that ScEtOH at 10 μg/mL led to 54 and 51% of inhibition, respectively, for the hemin and HRP systems. In the MPO system...

Changes in the metabolism of methionine can cause hyperhomocysteinemia, inducing a triad of atherosclerosis, hypertension, and increased oxidative stress. The generation of free radicals and oxidative damage to DNA is important in the liver damage caused by ethanol. In this study, the effect of methionine overload associated or otherwise with acute administration of ethanol on homocysteine values, damage to DNA, lipoperoxidation and vitamin E was evaluated. Thirty rats were divided into 3 groups: Group Ethanol 24 hours (EG24), Group Methionine 24 hours (MG24), and Group Methionine and Ethanol 24 hours (MEG24). TBARS, vitamin E, GS and, homocysteine values were determined and the Comet assay was carried out. Increased GSH, vitamin E and homocysteine levels were observed for MEG24, and increased TBARS were observed in EG24. The Comet assay showed an increase in DNA damage in EG24 and DNA protection in MEG24. The administration of ethanol decreased antioxidant levels and increased TBARS, indicating the occurrence of oxidative stress with possible DNA damage. The combination of methionine and ethanol had a protective effect against the ethanol-induced damage, but increased the levels of homocysteine.

A total of 75 healthy male dry cell industry workers exposed to carbon for 5, 8 and 10 years were compared with 48 controls matched for age and economic status with respect to free radical generation, lipid peroxidation and antioxidant levels. Lymphocytes were seperated from the whole blood and used for estimation of free radicals and antioxidants. Plasma lipid peroxidation products were estimated in the form of thiobarbituric acid reactive substances. Significant increase in free radical generation and lipid peroxidation products were observed in carbon exposed population than controls, and the increase was found to be significant with increase in the period of exposure. The levels of antioxidants i.e., superoxide dismutase (SOD) and catalase were found to decrease with the increase in exposure to carbon in industrial workers. These results suggest that exposure to carbon augments free radical generation, lipid peroxidation and promotes decline in antioxidant enzymes.

Multiple mechanisms underlie the human aging process, but interest continues in the role that free radicals and antioxidants may play. The concentrations of lymphocyte free radical generation (O2−& H2O2), DNA damage and antioxidant enzyme levels (glutathione Stransferase, superoxide dismutase and catalase) were evaluated in 110 healthy individuals with an age range of 20–80 years. The antioxidant enzyme levels were significantly less in very old age when compared to young. Moreover, the levels of free radical concentration and DNA damage were increased in the same age group with respect to younger group. Cigarette smoking had a positive relation with free radicals and DNA damage, and inverse relation with antioxidants. On the other hand, body mass was found to have positive relation with free radical generation only. The data indicate that depletion of antioxidant enzyme levels would render the older people more susceptible to free radical stress and DNA damage.

Modification of platelet proteins by free radicals and glycation has been studied in the present work, as anin vitro model. The results of the two parameters, SDS-PAGE and carbonylation study are quite corroborative. We observed that the inducers like ferrous sulphate, ascorbate (mainly in supraphysiological concentration) and glucose attack the protein in a dose dependent manner, of which ferrous sulphate is most potent. Proteins from aged and degenerative conditions like malignancy and diabetes mellitus have suffered greater damage than normal adult and foetal proteins. The individual life expectancy in terms of biological versus chronological age may also be worked out from the individual stress level.

Free radicals and oxidants play a dual role as both toxic and beneficial compounds, since they can be either harmful or helpful to the body. They are produced either from normal cell metabolisms in situ or from external sources (pollution, cigarette smoke, radiation, medication). When an overload of free radicals cannot gradually be destroyed, their accumulation in the body generates a phenomenon called oxidative stress. This process plays a major part in the development of chronic and degenerative illness such as cancer, autoimmune disorders, aging, cataract, rheumatoid arthritis, cardiovascular and neurodegenerative diseases. The human body has several mechanisms to counteract oxidative stress by producing antioxidants, which are either naturally produced in situ, or externally supplied through foods and/or supplements. This mini-review deals with the taxonomy, the mechanisms of formation and catabolism of the free radicals, it examines their beneficial and deleterious effects on cellular activities, it highlights the potential role of the antioxidants in preventing and repairing damages caused by oxidative stress, and it discusses the antioxidant supplementation in health maintenance.

Over the past few decades, the free radicals and antioxidants have attracted tremendous importance in the field of dentistry. Depending on the level of free radicals in the body, they can either be harmful or helpful. Antioxidants are the substances that interact with and stabilize free radicals thereby protecting cells from the damage caused by free radicals. The indigenous antioxidants may be useful in preventing the harmful effects of oxidative stress. The present article presents a review on the free radicals formation, their role in disease pathogenesis, antioxidants and their potential role in endodontics.

Free radicals have been implicated in various pathological conditions such as, stroke, aging and ischemic heart disease (IHD), as well as neurodegenerative diseases like Alzheimer’s, Parkinson’s, and Huntington’s disease. The role of antioxidants in protection from the harmful effects of free radicals has long been recognized. Trapping extremely reactive free radicals and eliminating them from circulation has been shown to be effective in animal models. Nitrone-based free radical traps have been extensively explored in biological systems. Examples include nitrones such as PBN, NXY-059, MDL-101,002, DMPO and EMPO. However, these nitrones have extremely high oxidation potentials as compared to natural antioxidants such as Vitamin E (á-tocopherol), and glutathione. Becker et al. (1995) synthesized novel azulenyl nitrones, which were shown to have oxidation potentials much lower than that of any of the previously reported nitrone based spin traps. Another azulenyl nitrone derivative, stilbazulenyl nitrone (STAZN), was shown to have an even lower oxidation potential within the range of natural antioxidants. STAZN, a second generation free radical trap, was found to be markedly superior than the two most studied nitrones, PBN and NXY-059...

Blood RBC's were used to study the role of polyamines, putrescine, spermidine and spermine individually as antioxidants against the peroxidative action of H2O2 which leads to haemolysis of erythrocytes. Results indicated that putrescine did not act as antioxidant at all concentrations used in our studies. However, spermidine and spermine suppressed peroxidative changes in RBC's due to the action of H2O2 and this suppression was greater with higher concentration of these individual polyamines used, separately. Further, all the three polyamines decreased haemolysis of erythrocytes at all concentrations studied. The action of putrescine to suppress haemolysis of RBC's without showing antioxidant property hypothetically suggests that these properties of respective polyamines may have independent mechanism of action.

In recent years, there has been a great deal of attention toward the field of free radical chemistry. Free radicals reactive oxygen species and reactive nitrogen species are generated by our body by various endogenous systems, exposure to different physiochemical conditions or pathological states. A balance between free radicals and antioxidants is necessary for proper physiological function. If free radicals overwhelm the body's ability to regulate them, a condition known as oxidative stress ensues. Free radicals thus adversely alter lipids, proteins, and DNA and trigger a number of human diseases. Hence application of external source of antioxidants can assist in coping this oxidative stress. Synthetic antioxidants such as butylated hydroxytoluene and butylated hydroxyanisole have recently been reported to be dangerous for human health. Thus, the search for effective, nontoxic natural compounds with antioxidative activity has been intensified in recent years. The present review provides a brief overview on oxidative stress mediated cellular damages and role of dietary antioxidants as functional foods in the management of human diseases.

Numerous investigations exist about the alterations that oxygen free radicals can provoke on biomolecules; these modifications can be
prevented and/or reversed by different antioxidants agents. On the other hand, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), a stable
nitrogen synthetic radical, is used to evaluate the antioxidant capacity of medicinal herbal products; however, the structural changes that
this radical provoke on the herbal active principles are not clear yet. In this work, we compared the redox reactivity of oxygen free radicals
and DPPH radical on phospholipids and protein thiol groups present in rat liver microsomes. Cu2+/ascorbate was used as generator
system of oxygen free radical and as antioxidant, an extract of Buddleja globosa’s leaves. Cu2+/ascorbate provoked microsomal lipid
peroxidation, microsomal thiols oxidation and oxygen consumption; all of these phenomena were inhibited by B. globosa extract. On
the other hand, DPPH was bleached in different extension by the herbal extract and phosphatidyl choline; beside, DPPH decreased
microsomal thiols content, but this phenomenon were not prevented by the herbal extract. Furthermore, DPPH did not induce oxygen
consumption and neither modified the oxygen consumption induced by Cu2+/ascorbate. Distinct redox mechanisms may explain the differences
between the reactivity of DPPH and oxygen free radicals on biomolecules...

The traditional methods of the biology, based on illustrative descriptions
and linear logic explanations, are discussed. This work aims to improve this
approach by introducing alternative tools to describe and represent complex
biological systems. Two models were developed, one mathematical and another
computational, both were made in order to study the biological process between
free radicals and antioxidants. Each model was used to study the same process
but in different scenarios. The mathematical model was used to study the
biological process in an epithelial cells culture; this model was validated
with the experimental data of Anne Hanneken's research group from the
Department of Molecular and Experimental Medicine, published by the journal
Investigative Ophthalmology and Visual Science in July 2006. The computational
model was used to study the same process in an individual. The model was made
using C++ programming language, supported by the network theory of aging.; Comment: 4 pages, 5 figures. Treball de Recerca, gener de 2012

Known to mankind since primitive man, the plants are used for food and to cure diseases. It is evident that a diet with essential nutrients and bioactive substances plays an important role on preventing and curing chronic diseases. Free radicals production occurs in the body, such as a physiological process. Substantial evidences had shown that free radicals and other oxidants are responsible for aging, autoimmune diseases, inflammatory diseases and degenerative diseases as cancer, cardiovascular disease, liver disease, cataracts, immunologic decline and brain dysfunctions. Antioxidants protect the body, being able to intercept free radicals from cellular metabolism or exogenous sources, avoiding cellular integrity losses and injuries. Fresh vegetables contain numerous phytochemicals, plant metabolites, especially phenolic compounds, nitrogen compounds, carotenoids, ascorbic acid and tocopherols. These compounds have significant antioxidant activity, and are associated with lower incidence and mortality from chronic diseases, especially cancer, in humans. Key-words: antioxidants, free radicals, secondary metabolites